1 The mole and Avogadro’s constant

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Oxford Textbook Pages : 22 - 29

CGP Revision Guide Pages : 14 - 15

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Show Specification Ref : 3.1.2.1, 3.1.2.2, 3.1.2.3

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Question 1 / 5

January 2010 QP – Unit 1 AQA Chemistry A-level_question_2 pmt areas outside the box will not be scanned for marking ammonium sulfate reacts with sodium hydroxide to form ammonia sodium sulfate and water as shown in the equation below nh so s naoh aq nh g na so aq h o l a a g sample of ammonium sulfate reacted completely with cm of a sodium hydroxide solution i calculate the amount in moles of nh so in g of ammonium sulfate a marks a ii hence calculate the amount in moles of sodium hydroxide which reacted a mark iii calculate the concentration in moldm of the sodium hydroxide solution used mark b calculate the percentage atom economy for the production of ammonia in the reaction between ammonium sulfate and sodium hydroxide marks wmp jan chem c ammonia is manufactured by the haber process nh n h calculate the percentage atom economy for the production of ammonia in this process mark d a sample of ammonia gas occupied a volume of m at c and a pressure of kpa the gas constant r jk mol calculate the amount in moles of ammonia in this sample marks extra space e glauber s salt is a form of hydrated sodium sulfate that contains by mass of sodium sulfate hydrated sodium sulfate can be represented by the formula na so xh o where x is an integer calculate the value of x marks extra space pmt areas outside the box will not be scanned for marking turn over wmp jan chem
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Question 2 / 5

January 2013 QP – Unit 1 AQA Chemistry A-level_question_5 section b answer all questions in the spaces provided do not write outside the box ammonia is used to make nitric acid hno by the ostwald process three reactions occur in this process reaction reaction reaction nh g o g no g h o g no g o g no g no g h o i hno aq no g a in one production run the gases formed in reaction occupied a total volume of m at c and kpa calculate the amount in moles of no produced give your answer to significant figures the gas constant r j k mol marks extra space wmp jan chem do not write outside the box b in another production run kg of ammonia gas were used in reaction and all of the no gas produced was used to make no gas in reaction b i calculate the amount in moles of ammonia in kg marks b ii calculate the mass of no formed from kg of ammonia in reaction assuming an yield give your answer in kilograms if you have been unable to calculate an answer for part b i you may assume a value of mol this is not the correct answer marks extra space question continues on the next page turn over wmp jan chem do not write outside the box c consider reaction in this process no g h o i hno aq no g calculate the concentration of nitric acid produced when mol of no is reacted with water and the solution is made up to cm marks extra space d suggest why a leak of no gas from the ostwald process will cause atmospheric pollution mark e give one reason why excess air is used in the ostwald process mark f ammonia reacts with nitric acid as shown in this equation nh hno nh no deduce the type of reaction occurring mark wmp jan chem
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Question 3 / 5

June 2010 QP – Unit 1 AQA Chemistry A-level_question_3 do not write outside the box in this question give all your answers to three significant figures magnesium nitrate decomposes on heating to form magnesium oxide nitrogen dioxide and oxygen as shown in the following equation mg no s mgo s no g o g a thermal decomposition of a sample of magnesium nitrate produced g of magnesium oxide a i calculate the amount in moles of mgo in g of magnesium oxide marks a ii calculate the total amount in moles of gas produced from this sample of magnesium nitrate mark b in another experiment a different sample of magnesium nitrate decomposed to produce mol of gas calculate the volume in dm that this gas would occupy at k and pa the gas constant r j k mol marks extra space wmp jun chem do not write outside the box c a mol sample of magnesium oxide produced from the decomposition of magnesium nitrate was reacted with hydrochloric acid mgo hcl mgcl h o c i calculate the amount in moles of hcl needed to react completely with the mol sample of magnesium oxide mark c ii this mol sample of magnesium oxide required cm of hydrochloric acid for complete reaction use this information and your answer to part c i to calculate the concentration in mol dm of the hydrochloric acid mark turn over for the next question turn over wmp jun chem do not write outside the box a there are several oxides of nitrogen an oxide of nitrogen contains by mass of nitrogen determine the empirical formula of this oxide marks extra space b give one reason why the oxide no is a pollutant gas mark c the oxide no reacts with oxygen to form nitrogen dioxide write an equation for this reaction mark d explain how no is produced in the engine of a motor vehicle marks e write an equation to show how no is removed from the exhaust gases in motor vehicles using a catalytic converter mark wmp jun chem
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Question 4 / 5

June 2012 QP – Unit 1 AQA Chemistry A-level_question_5 section b answer all questions in the spaces provided do not write outside the box a boron trichloride bcl can be prepared as shown by the following equation b o s c s cl g bcl g co g a sample of boron oxide b o was reacted completely with carbon and chlorine the two gases produced occupied a total volume of cm at a pressure of kpa and a temperature of k calculate the mass of boron oxide that reacted give your answer to significant figures the gas constant r j k mol marks extra space wmp jun chem do not write outside the box b boron trichloride can also be prepared from its elements write an equation for this reaction explain why boron trichloride has a trigonal planar shape with equal bond angles marks extra space c i boron trichloride is easily hydrolysed to form two different acids as shown in the following equation bcl g h o i h bo aq hcl aq calculate the concentration in mol dm of hydrochloric acid produced when g of boron trichloride are added to water to form cm of solution give your answer to significant figures marks extra space c ii boric acid h bo can react with sodium hydroxide to form sodium borate and water write an equation for this reaction mark question continues on the next page turn over wmp jun chem do not write outside the box d boron trichloride can be reduced by using hydrogen to form pure boron bcl g h g b s hcl g calculate the percentage atom economy for the formation of boron in this reaction apart from changing the reaction conditions suggest one way a company producing pure boron could increase its profits from this reaction marks extra space e a different compound of boron and chlorine has a relative molecular mass of and contains of boron by mass calculate the molecular formula of this compound show your working marks extra space copyright aqa and its licensors all rights reserved end of questions wmp jun chem
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Question 5 / 5

June 2013 QP – Unit 1 AQA Chemistry A-level_question_1 section a answer all questions in the spaces provided do not write outside the box the mass spectrum of the isotopes of element x is shown in the diagram relative abundance m z a define the term relative atomic mass marks b use data from the diagram to calculate the relative atomic mass of x give your answer to one decimal place marks wmp jun chem do not write outside the box c identify the ion responsible for the peak at mark d identify which one of the isotopes of x is deflected the most in the magnetic field of a mass spectrometer give a reason for your answer isotope reason marks e in a mass spectrometer the relative abundance of each isotope is proportional to the current generated by that isotope at the detector explain how this current is generated marks f x and zn are different elements explain why the chemical properties of x and zn are different mark turn over wmp jun chem do not write outside the box a the hydrocarbon but ene c h is a member of the homologous series of alkenes but ene has structural isomers a i state the meaning of the term structural isomers marks a ii give the iupac name of the position isomer of but ene mark a iii give the iupac name of the chain isomer of but ene mark a iv draw the displayed formula of a functional group isomer of but ene mark wmp jun chem
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